In civil engineering sector all civil engineers are well familiar with the term “reinforced concrete”. To make concrete useful for reinforcement there are so many metals available such as cast iron, aluminum, etc. But engineers mostly prefer mild steel as reinforcing material in reinforced concrete.
Steel, which has high tensile strength, is used with concrete in order to counteract the concrete's low tensile strength and ductility. The main purpose of inclusion of steel is resist tensile stress in particular regions of the concrete that may cause structural failure or cracking.
Question may arise why only steel has to be used when there are many materials, which have more tensile strength than steel, available. Well that's because of the compatibility and understanding between the steel and concrete. Mainly because of the following reasons:
- Mild steel is used for reinforcement with concrete because the thermal expansion coefficient of concrete and mild steel are almost same equal to 12*10^-6. So in atmosphere changes the approximate same contraction or expansion occurs in steel and concrete owing to which no bond breakage take place between concrete and steel. If we use other material instead of mild steel then we have to design also for thermal stress.
- Cement paste in concrete conforms to the surface of steel after it gets hardened, permitting any stress to be transmitted efficiently between the two materials. Moreover, steel bars are roughened or corrugated to further improve the bond or cohesion between the concrete and steel.
- The alkali chemical reaction in the hardened cement paste forms a passivating layer on the steel surface to make it much resistant to corrosion.
However, to give optimum results, reinforcement needs to have the following properties at least:
- Ductility
- Resistance against corrosion
- Bond with concrete
- High relative strength
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| Source : civildigital.com |
